Wound treatment apparatus

ABSTRACT

A wound treatment apparatus is disclosed to provide vacuum therapy to a wound associated with a patient. The wound treatment apparatus comprises a control unit comprising an alarm and a display displaying an alarm log providing information associated with each activation of the alarm. The display also displays information to instruct a user how to operate the wound treatment apparatus. A method of calibrating the control unit is disclosed.

This disclosure is a continuation-in-part of U.S. application Ser. No.09/725,666, which was filed Nov. 29, 2000 and which is herebyincorporated by reference herein.

BACKGROUND AND SUMMARY

The present disclosure relates to wound treatment apparatus for use withvacuum bandages of the type that dispenses fluid to a wound and drawsfluid away from the wound.

Medical professionals, such as nurses and doctors, routinely treatpatients having surface wounds of varying size, shape, and severity. Itis known that controlling the topical atmosphere adjacent a wound canenhance the healing process. For example, by applying medicinal agentsor even water over a wound, dirt and bacteria are either killed orwashed away, thereby promoting healing. In addition, applying a negativepressure or vacuum to a wound draws out exudate, which might containdirt and bacteria, from the wound to further promote healing.

Conventional treatment of a surface wound involves placement of apacking or dressing material, such as cotton, gauze, or otherbandage-like material directly in contact with the patient's wound.Often there is a need to change the dressing material frequently becauseit becomes saturated with exudate discharged from the wound. Somedressings include an apparatus attached thereto for applying a vacuumthrough the bandage to the wound to draw exudate and promote healing.

According to the present disclosure, a method for calibrating a controlunit adapted to provide a negative pressure through a vacuum woundbandage associated with a wound of a patient comprises positioning afirst pressure sensor in communication with the control unit. The methodcomprises correlating a first output of a second pressure sensor of thecontrol unit to a first calibration pressure when the first pressuresensor senses the first calibration pressure and correlating a secondoutput of the second pressure sensor to a second calibration pressurewhen the second pressure sensor senses the second calibration pressure.

According to another aspect of the disclosure, the control unitcomprises an alarm and a display. The display displays an alarm logproviding information associated with each activation of the alarm.

According to another aspect of the disclosure, a wound treatmentapparatus is adapted for use with the vacuum wound bandage associatedwith the wound of the patient to provide negative pressure through thevacuum wound bandage to the wound. The wound treatment apparatuscomprises a user input control and an electronic display displayinginformation comprising a graphical representation of the user inputcontrol and text associated with the graphical representation toinstruct a user when to operate the user input control. In someembodiments, the electronic display displays information that instructsthe user how to operate the wound treatment apparatus during normaloperation of the wound treatment apparatus and the information isexecutable to operate the wound treatment apparatus when the display isdisplaying the information.

Additional features and advantages of the apparatus will become apparentto those skilled in the art upon consideration of the following detaileddescriptions exemplifying the best mode of carrying out the apparatus aspresently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

The illustrative apparatus will be described hereinafter with referenceto the attached drawings, which are given as non-limiting examples only,in which:

FIG. 1 is a perspective view of a wound treatment apparatus coupled to abandage attached to a patient;

FIG. 2 is a block diagram of the wound treatment apparatus of FIG. 1;

FIG. 3 is a schematic diagram of the wound treatment apparatus of FIG.1;

FIG. 4 is a side cross-sectional view of the wound treatment apparatusalong the lines A—A of FIG. 1;

FIG. 5 is a schematic block diagram of the vacuum evacuating subsystemof the wound treatment apparatus of FIG. 1;

FIG. 6 is a cross-sectional view of a waste disposal canister of thewound treatment apparatus along the lines B—B of FIG. 1;

FIG. 7 is a partially exploded perspective view of the wound treatmentapparatus of FIG. 1 with the waste canisters removed;

FIG. 8 is a perspective view of another embodiment of the woundtreatment apparatus;

FIG. 9 is a side diagrammatic view of the vacuum bandage and portions ofthe wound treatment apparatus of FIG. 1;

FIG. 10 is a perspective view of the wound treatment apparatus of FIG. 1with the waste canister removed;

FIG. 11 is a front elevational view of a waste canister;

FIG. 12 is a side elevational view of the waste canister of FIG. 11; and

FIG. 13 is a top view of the waste canister of FIG. 11.

FIG. 14 is a perspective view of another wound treatment apparatusshowing a pair of canisters arranged for insertion into respectivereceptacles formed in the sides of a housing of a control unit andshowing a fluid source arranged for insertion into a receptacle formedin the front of the housing;

FIG. 15 is an enlarged elevation view of a latch for a door of the woundtreatment apparatus of FIG. 14 showing the latch in a release position;

FIG. 16 is a view similar to FIG. 15 showing the latch in a latchedposition;

FIG. 17 is a fragmentary sectional view showing a syringe having aflange received by grooves of the door and the housing to retain abarrel of the syringe in place;

FIG. 18 is a perspective view of the rear of a control unit of the woundtreatment apparatus of FIG. 14 showing a carrying handle at the top ofthe control unit and a mounting bracket on a rear wall of the controlunit;

FIG. 19 is a perspective view of the rear of the control unit of FIG. 18with a rear wall removed;

FIG. 20 is an exploded perspective view of a waste collection canisterof the control unit;

FIG. 21 is a fragmentary perspective view of a portion of the canisterof FIG. 20 and a portion of a receptacle of the housing in which thecanister is received;

FIG. 22 is a side sectional view of the canister partially inserted intothe receptacle;

FIG. 23 is a side sectional view similar to FIG. 22 of the canisterinstalled within the receptacle;

FIG. 24 is an enlarged elevation view of the interface between the latchand a wall of the receptacle showing lugs of the latch aligned withlug-receiving spaces of an aperture formed in the receptacle wall;

FIG. 25 is an enlarged elevation view, similar to FIG. 24, showing thelugs of the latch misaligned with the lug-receiving spaces of theaperture to retain the canister in the receptacle;

FIG. 26 is a sectional view taken along line 26—26 of FIG. 25 showingengagement between the lugs and the receptacle wall;

FIG. 27 is a diagrammatic view of portions of the wound treatmentapparatus of FIG. 14;

FIG. 28 is a diagrammatic view of a three-chambered muffler.

FIG. 29 is an elevational view of a user interface of the woundtreatment apparatus of FIG. 14 showing the user interface having a leftside which is associated with a first system for providing vacuumtherapy to a first wound of a patient and a right side which isassociated with a second system for providing vacuum therapy to a secondwound of the patient, each side having a display and a plurality of usercontrols;

FIG. 30 is an elevational view of the user interface showing a softwarerevision level on the left display and the number of seconds remainingto complete a system self-test on the right display;

FIG. 31 is an elevational view of the user interface showing acalibration screen on the left and right displays to calibrate pressuresensors of the wound treatment apparatus;

FIG. 32 is a diagrammatic view of components of one of the two systemsof the wound treatment apparatus showing a pressure sensor coupled to aleft inlet port of a waste collection canister to calibrate a pressuresensor coupled to a right pressure port of the waste collectioncanister;

FIG. 33 is an elevational view of the user interface showing alarm logsproviding information associated with activations of alarms of the woundtreatment apparatus;

FIG. 34 is an elevational view of the user interface showing a screen inwhich a user is prompted to select whether the next application of thewound treatment apparatus will be for a new patient or for the samepatient as the most previous application of the wound treatmentapparatus;

FIG. 35 is an elevational view of the user interface showing the leftand right displays prompting a user to select one of four modes ofoperation for the associated systems of the wound treatment apparatus;

FIG. 36 is an elevational view of the user interface showing the systemassociated with the left display operating in a Continuous mode andprompting a user to enter a desired negative pressure to be applied tothe first wound and showing the system associated with the right displayoperating in a Profile mode and prompting the user to enter a maximumnegative pressure that can be applied to the second wound;

FIG. 37 is an elevational view of the user interface showing the systemassociated with the left display operating normally in Continuous modeand showing the system associated with the right display operating inProfile mode and prompting the user to enter a minimum negative pressurethat can be applied to the second wound;

FIG. 38 is an elevational view of the user interface showing operationof the system associated with the left display paused for a period oftime and showing the system associated with the right display operatingnormally in the Profile mode;

FIG. 39 is an elevational view of the user interface showing eachdisplay providing a record of activity of the associated system which isoperating in a History mode;

FIG. 40 is an elevational view of the user interface showing the systemassociated with the left display operating in History mode and thesystem associated with the right display operating an Off mode in whichactivity of that system is suspended;

FIG. 41 is an elevational view of the user interface showing the leftand right displays providing information for operating respective flushor irrigation mechanisms of the wound treatment apparatus;

FIG. 42 is an elevational view of the user interface showing the leftdisplay providing information for operating the respective irrigationmechanism and the right display providing information associated with analarm condition; and

FIGS. 43-48 are elevational views of the user interface showing the leftand right displays providing information associated with various alarmconditions.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplification set out hereinillustrates several embodiments of the apparatus, and suchexemplification is not to be construed as limiting the scope of thisdisclosure in any manner.

DETAILED DESCRIPTION OF DRAWINGS

An embodiment of wound treatment apparatus 2 is shown in FIG. 1. Woundtreatment apparatus 2 comprises a central unit housing 4, having woundtreatment systems 6, 8 appended to each side of housing 4. A userinterface 10 is shown positioned between each treatment system 6, 8.Central unit housing 4 is configured to be a portable unit allowing auser, such as a caregiver, to move housing 4 to wherever the patient islocated and to close proximity to the wound or wounds. Housing 4 isshown having a handle portion 12 to assist the caregiver in movinghousing 4. FIG. 1 also shows wound treatment system 6 coupled to abandage 14 attached to a patient's leg 16. Dispensing and evacuatingtubes 18, 20 are coupled to both bandage 14 and system 6. Specifically,dispensing tube 18 is coupled to a luer-lok port 22 extending fromsyringe 24. Syringe 24 is filled with a fluid, typically saline, thatempties through tube 18 and into bandage 14, and ultimately onto a wound300 positioned under bandage 14. (See also FIG. 9.) After contactingwound 300, the fluid and exudate from wound 300 are drawn from bandage14 through evacuating tube 20 and into a waste canister 26 where it iscollected. It is contemplated that the canister 26 can be discarded whenfilled and replaced with a new canister 26.

Apparatus 2 comprises a second system 8 on the opposite side of housing4 from system 6. This configuration allows two wounds to be treatedsimultaneously with separate bandages, yet, under the control of asingle housing 4. Second bandage 15, as part of system 8, is coupled todispensing and evacuating tubes 28, 30, respectively, to perform thesame functions as described for system 6. (See FIG. 2.) User interface10 is provided to allow the caregiver to control either or both systems6, 8, to dispense fluid from either or both syringes 24, 224, and toevacuate from either or both bandages 14, 15. It is contemplated thateach wound treatment system 6, 8 will work independent of each other,thus, allowing the caregiver flexibility to apply an appropriate and,yet, possibly different level of treatment to each wound.

The arrangement of systems 6, 8 relative to user interface 10 on housing4 allows convenient interaction between systems 6, 8 and the caregiver.For example, syringes 24, 224 are conveniently positioned on oppositesides of user interface 10. Each syringe is partially covered by doors32, 33 on the front of housing 4. Each door 32, 33 swings outwardlyabout hinges 34, 36, allowing syringes 24, 224 to be removed andreplaced. Similarly, waste canisters 26, 27 are each positioned in acavity 9 provided on each side of housing 4. (See FIG. 7.) Each canister26, 27 includes a grip portion 40 for convenient removal andreplacement. Canisters 26, 27 are illustratively secured into eachcavity by a friction fit. (See FIG. 6.) It is appreciated, however, thatsyringes 24, 224 can be secured to other locations on housing 4.

The portability of apparatus 2 allows a caregiver to position it nearthe patient in preparation for treatment wherever the patient islocated. To prepare apparatus 2 for treatment, the caregiver securessyringes 24, 224, which contain fluid, to apparatus 2 in a mannerdescribed in greater detail below. The caregiver then couples tube 18 toport 22 and bandage 14, and tube 20 to bandage 14 and waste canister 26,for treatment of one wound. The caregiver then couples tube 28 to port222 and bandage 15, and tube 21 to bandage 15 and waste canister 27, fortreatment of a second wound. (See also FIG. 2.) The caregiver, throughthe use of user interface 10 can treat the patient by selectivelyirrigating the wounds with fluid and drawing exudate and the fluid fromthe wounds.

A diagram depicting how wound apparatus 2 operates is shown in FIG. 2. Acontroller 50 is provided in housing 4 and is an electronic control unitthat controls apparatus 2. Controller 50 receives user input from andprovides feedback to user interface 10 through lines 52, 54,respectively. It is contemplated that controller 50 will processinformation from both systems 6, 8, and provide appropriate andindependent input to each system. Controller 50 also monitors the statusof all various sensors, and provides input for the valves and motors, asdiscussed in further detail herein. Illustratively, user interface 10 iscomposed of a conventional graphic liquid crystal display (LCD) and amembrane switch panel.

A power supply 56 provides power to controller 50 and all the attendantsystems in housing 4. Power supply 56 can be a conventional externalwall socket supply (not shown), or be a battery pack supply (also notshown), or even be variations of both (e.g., a wall socket supply with abattery pack supply). Illustratively, power supply 56 is a medical gradepower supply providing an output of about 65 watts and a voltage ofabout 12VDC. It is contemplated that the power supply can be configuredfor 120V/60 Hz or 220-240V/50 Hz depending on whether housing 4 is usedin America or Europe. Illustratively, the battery power provides thedevice with power to operate for about 60 minutes without connection toan external power source. It is further contemplated that the batteriescan be rechargeable, and store energy when the device is connected to anexternal wall socket.

An attitude sensor 58 is provided in communication with controller 50through line 60. Attitude sensor 58 is, illustratively, a tilt switchwhich provides feedback to controller 50. If the switch is,illustratively, in the closed position, controller 50 will continue tooperate, but if the switch opens, controller will shut systems 6, 8down. For example, sensor 58 disables systems 6, 8 if housing 4 tilts ator greater than a predetermined amount, such as 45° from vertical in anydirection.

It is contemplated that controller 50, user interface 10, power supply56, and attitude sensor 58 are all common to and all operate with bothsystems 6, 8. Each system 6, 8 further comprises fluid dispensing andvacuum evacuating subsystems 62, 64 and 66, 68. Fluid dispensingsub-system 62 comprises a syringe 24 having a plunger 70. (See also FIG.4.) Syringe 24 is, illustratively, a standard 60-ml medical syringeutilizing a luer-lok port 22. Plunger 70 is a conventional plunger thatextends into syringe 24 to dispense fluid through luer-lok port 22. Asyringe drive motor 72 is, illustratively, a 12VDC brushless electricmotor or stepper motor configured to provide rotational energy to asyringe drive 74. (See FIG. 4.) When a signal is sent from controller 50along line 76 to syringe drive motor 72, motor 22 applies torque andangular velocity to syringe drive 74 which is, illustratively, a powerscrew 322. (See also FIG. 4.) Power screw 322 translates rotationalmovement of the syringe drive motor 72 into translational movement. Thedrive has a guide 80 to limit a plunger interface 78 to motion along oneaxis. In the illustrated embodiment, syringe drive 72 provides about5.25 inches (13.3 cm) of travel of plunger interface 78, indicated byreference numeral 82, to evacuate the fluid contained in syringe 24.(See also FIG. 4.) Furthermore, syringe drive motor 72 and syringe drive74, as a system, provide about 27 pounds of linear force at a velocityof 1.45 inches (3.7 cm) per second to the plunger interface 78. Theresulting force created by the fluid exiting syringe 24 creates,illustratively, 4-PSIG to 6-PSIG positive pressure at wound 300.

A syringe home sensor 84 receives information from plunger interface 78,and provides feedback to controller 50 when syringe capture mechanism 88reaches its home position 79. A syringe full travel sensor 86 determineswhen syringe 24 is fully evacuated by sensing when plunger interface 78has reached full travel. After sensor 86 has been activated, controller50 resets plunger interface 78 to home position 79 once syringe 24 isremoved.

Syringe capture mechanism 88 holds syringe 24 in place when thecaregiver places syringe 24 in apparatus 2. (See also FIG. 4.) Capturemechanism 88 is also configured to allow the caregiver to releasesyringe 24 from apparatus 2 when it is empty. Capture mechanism 88further includes a syringe sensor 90 that provides feedback tocontroller 50 through line 92 when syringe 24 is properly held incapture mechanism 88. Controller 50 prevents system 6 from operating ifsensor 90 does not detect syringe 50 being properly held in capturemechanism 88.

Connectors 94, 96 are provided at opposed ends of dispensing tube 18.Either one or both connectors 94, 96, when closed, block flow fromsyringe 24 to bandage 14. Such connectors 94, 96 allow the patient to bedisconnected from apparatus 2 without having to remove bandage 14 oreven shut apparatus 2 down.

A manual port 98 is also attached to dispensing tube 18 by an auxiliarytube 100. Port 98 permits the caregiver to attach a dispensing containerto the system to manually dispense fluid into bandage 14. It isappreciated, however, that port 98 is configured to be closed while nosyringe is attached to maintain a closed system.

The syringe and drive are illustrated as one approach for providing afluid source and a drive for irrigating a wound bed. It will beappreciated that containers other than syringes may be operated by adrive to expel irrigation fluid toward a wound surface. For example, anytype of container of fluid may be squeezed or reduced in volume by adrive mechanism to expel fluid. Also, as discussed in connection withFIG. 8, a container may be held at an elevated position to provide headpressure for irrigation fluid.

Connectors 104, 106, similar to connectors 94, 96, are provided atopposed ends of evacuating tube 20. Either one or both connectors 104,106, when closed, block flow from bandage 14 to waste canister 26. Suchconnectors 104, 106 also allow the patient to be disconnected fromapparatus 2 without having to remove bandage 14 or having to shut downapparatus 2.

Waste canister sensors 116, 118 are engaged when waste container 26 isproperly seated in apparatus 2. This prevents apparatus 2 from operatingwithout canister 26 seated properly in apparatus 2. As depicted in FIG.2, both sensors 116, 118 provide feedback to controller 50 through lines120, 122, confirming to the caregiver that canister 26 is seatedproperly in apparatus 2.

In the illustrated embodiment, waste canister 26 is a disposable unitthat “snaps into” side portion 38 of housing 4. (See also FIGS. 1 and6.) Illustratively, canister 26 includes a window (not shown) to allowmonitoring of the fluids. Illustratively, the fluid capacity of canister26 is about 500-ml.

The illustrated embodiment of waste canister 26 further includes ahydrophobic filter 108 that is in communication with both evacuatingtube 20 and vacuum pump 110. (See also FIG. 6.) Such filter 108 isconfigured to allow air, but not liquid, to pass. Accordingly, as fluidis drawn into canister 26, fluid is deposited into waste canister 26while the vacuum continues through filter 108 and pump 110.Illustratively, filter 108 is a 1.0-micron hydrophobic filter fixed intorear wall 407 of canister 26. (See FIG. 6.) Hydrophobic filter 108 alsoserves as a canister full mechanism 114 or valve that shuts off thevacuum supply to the canister 26 when the fluid level exceeds the “full”level 420. Because hydrophobic filter 108 prevents fluid from passing,once fluid covers filter 108, vacuum is prevented from passing as well.The absence of any vacuum in the system will cause the system to shutdown.

Vacuum pump 110 creates the negative pressure that is present throughcanister 26. For monitoring and controlling such negative pressure, thevacuum is present through several devices, including a vacuum pressuretransducer 124. Transducer 124 is coupled to line 128, extending fromcanister 26. (See FIG. 5.) Transducer 124 measures the negative pressurethat is present through canister 26. Transducer 124 then providesfeedback to controller 50 through line 128. Controller 50 monitors thenegative pressure by comparing the measured value from transducer 124with the caregiver-defined value entered into controller 50 through userinterface 10.

A proportional valve 130 is connected to line 126, through which thenegative pressure is present, and which comprises a flow orifice 132.(See also FIG. 5.) Flow orifice 132 selectively dilates or constricts,thereby controlling the negative pressure level through sub-system 66.Specifically, controller 50 provides a signal input to proportionalvalve 130 based on the level of the vacuum pressure determined fromfeedback of transducer 124 and comparing that level to thecaregiver-defined level. Orifice 132 then dilates or constricts, asnecessary, to produce the appropriate level of negative pressure.Illustratively, proportional valve 130 is fully constricted or closedwhen receiving no signal from controller 50, and dilates or opens toallow an illustrative maximum of two liters per minute at 250-mmHg(4.83-PSIG) vacuum when the proper signal from controller 50 is applied.

A vacuum regulator 134 is provided in line 126 between proportionalvalve 130 and pump 110 as a mechanical limit control for pump 110.Regulator 134 mechanically establishes a maximum level of negativepressure that is present in the system. Thus, vacuum pump 110 will notphysically be able to draw a vacuum from bandage 14 beyond the maximumpressure. Illustratively, such maximum negative pressure or vacuum is250-mmHg (4.83-PSIG). In addition, when proportional valve 130, pursuantto a signal from controller 50, creates a negative pressure less thanthe maximum negative pressure level, a port 136, coupled to regulator134, opens so that pump 110 can draw more air to maintain a sufficientflow through pump 110, to prevent it from becoming damaged. A first airfilter 137 is illustratively associated with port 136, between port 136and pump 110, to filter particulates from the air prior to reaching pump110. Illustratively, filter 137 is constructed of glass microfibers witha filtration rating of 25 microns. A second filter 139 is associatedwith pump 110 and an outlet 141. Filter 139 serves as an exhaust mufflerfor the air evacuated from pump 110.

Vacuum pump 110 is, illustratively, a diaphragm-type compressor thatflows about two liters per minute at 250-mmHg (4.83-PSIG) vacuum.Illustratively, vacuum pump 110 is mounted on the end of a single 12VDCbrushless motor 138 to drive the pump. It is appreciated, however, thatpump 110 can be of any other configuration, and mounted in any manner,so long as it draws a desired negative pressure through system 6. It isalso contemplated that a vacuum pump external to the housing 4 may be apart of the control system. For example, most medical facilities havevacuum ports near where patients are treated, each of which is served bya system vacuum (suction) pump. It is contemplated, therefore, that thepump 110 in the housing 4 may be an appropriate fitting which is, inturn, connected to a facility vacuum pump to provide a vacuum source tothe control system.

It is contemplated that port 136, filters 137, 139, electric motor 138,vacuum pump 110, and vacuum regulator 134 are all housed in a soundchamber 140. Illustratively, the interior of sound chamber 140 is linedwith a damping foil like the 3M Company's damping foil number 2552, forexample. Sound chamber 140 dampens vibration energy produced by thesecomponents, as well as assists in dissipating heat they generated.

As previously indicated, it is contemplated that controller 50, userinterface 10, power supply 56, and attitude sensor 58 are common to, andoperate with, both fluid dispensing and vacuum evacuating sub-systems62, 64 and 66, 68. Providing a second independently operable set ofsub-systems 64, 68 allows the caregiver to treat two wounds using asingle apparatus 2. Accordingly, second fluid dispensing and evacuatingsub-systems 64, 68 also shown in FIG. 2, comprise identical componentsas discussed regarding sub-systems 62, 66 and are labeled in acorresponding manner. For example, syringe motor drive 72 in sub-system62 is identified as syringe motor drive 172 in sub-system 64, and avacuum pump 110 in sub-system 66 is identified as vacuum pump 210 insub-system 68.

A schematic diagram of a portion of wound treatment apparatus 2 is shownin FIG. 3. Each system 6 and 8 is configured to operate in the samemanner. Specifically, FIG. 3 depicts the operation of system 6. Movementof plunger 70 into syringe 24 causes fluid stored in syringe 24 to exitinto tube 18 and into bandage 314 where it drains through orifices 302onto wound 300. Vacuum 110 applies a negative pressure through wastecanister 26 and bandage 314. Fluid and exudate are then drawn from wound300 out through tube 20 and into canister 26. The hydrophobic filter108, discussed in connection with FIG. 2, allows the vacuum to passthrough waste canister 26, yet, prevents any of the fluid from escaping,and depositing the fluid into pump 110.

The mechanism for moving plunger 70 into syringe 24, part of fluiddispensing sub-system 62, is shown in cross-sectional form in FIG. 4.The illustrated embodiment includes sub-system 62 positioned withinhousing 4. Specifically, a bracket frame 310 serves as the skeletalstructure for sub-system 62. Bracket 310 includes a base portion 312with an upwardly extending structural member 314 appending from one endthereof. A support portion 316 extends outwardly from member 314, and issuperposed above base portion 312. Extending from support portion 316 issyringe bracket 318. Syringe capture mechanism 88 is formed in bracket318, and is configured to receive syringe 24, as previously discussed.Bracket 318 and capture mechanism 88 are configured to suspend syringe24 with luer-lok port 22 directed upwardly. It is contemplated thatcapture mechanism 88 secures syringe 24 to bracket 318 by other means,including being friction-fitted, or secured with clips or bolts. To moveplunger 70, syringe drive 74 and plunger interface 78 are coupled toframe 310. Plunger interface 78 captures plunger 70 and provides upwardlinear motion to evacuate syringe 24. Interface 78 provides a releasemechanism for plunger 70 to remove syringe 24 at any position in thestroke.

Syringe drive 74 comprises syringe drive motor 72 and power screw 322.Power screw 322 is disposed through an aperture 324 in support portion316, and is rotatably coupled to motor 72. It is appreciated that motor72 can be a stepper or electric motor, for example. The lower end 326 ofpower screw 322 is positioned within a bearing cavity 328 within whichpower screw 322 rotates. Spaced in parallel to power screw 322 is guide80. Guide 80 is received in an aperture 330, also disposed in supportportion 316 at its upper end 332, and is received in cavity 334 at itslower end 336. Plunger interface 78 is configured to receive cap 338 ofplunger 70, and is coupled to a dual coupler 340. Dual coupler 340comprises two blocks 342, 344, each having bores 346, 348 disposed,respectively, there through. In the illustrated embodiment, bore 346 hasa smooth surface and is configured to receive guide 80. In contrast,bore 348 has a threaded surface and is configured to cooperate withthreads on power screw 322. Coupler 340 is movable upwardly anddownwardly in directions 350, 352. A hatched outline version of coupling340, indicated by reference numeral 354, is shown depicting plungerinterface 78 and plunger 70 moving upwardly in direction 350. As shownin FIG. 4, as plunger 70 is moved upwardly, head 356 is also movedupwardly, reducing the available space in syringe 24, thus, displacingany fluid in syringe 24 out of luer-lock port 22, thereby dispensing thefluid into tube 18 and into bandage 14. The movement of cap 356 isdepicted by the position of cap 356 in hatched lines moved to an upperposition indicated by reference numeral 358.

A cross-sectional view of waste canister 26 located in cavity 9 on side38 of housing 4 is shown in FIG. 6. Tube 20 is connected to acheck-valve assembly 400 coupled to recess 402 disposed in the frontwall 405 of canister 26. Check valve 400 is configured to allow fluidand exudate from bandage 14 to enter canister 26 and deposit in holdingspace 404 within canister 26, yet prevent any fluid already in space 404from exiting through valve 400. Check valve 400, thus prevents fluidfrom escaping when tube 20 is disengaged from valve 400. In addition,canister 26 can be discarded without any fluid escaping. Hydrophobicfilter 108 is located on the rear wall 407 of canister 26. A liquidsolidifier 29 is provided in space 404 to decease the fluidity of theexudate. This is a safety measure to lessen the chance of splashing orrun-off if canister 26 (or 27) is opened or broken.

Filter 108 in canister 26 is shown having an inlet 410 provided in space404 and an outlet 412 coupled to a connector 416 with a barrier ofhydrophobic material 414 provided there between. As previouslydiscussed, the hydrophobic material allows the vacuum to pass throughinlet 410 and outlet 412, yet prevents any fluid from passing. Similarto check valve 400, hydrophobic filter 108 too prevents any fluid fromescaping even when canister 26 is removed from housing 4. Outlet 412 offilter 108 is in communication with connector 416. Connector 416 isconfigured to receive and seal outlet 412 when canister is positioned incavity 9. Connector 416 is in communication with line 126 and ultimatelywith pump 110.

In the illustrated embodiment, hydrophobic filter 108 serves as both thecanister full mechanism 114 that shuts off the vacuum supply to thecanister 26 when the fluid level exceeds the “full” level as indicatedby reference numeral 420. When the fluid level is below inlet 410, asindicated by reference numeral 422, fluid continues to enter space 404through valve 400. When the fluid level 420 is above inlet 410, thefluid is acting as an air block. Fluid cannot pass through filter 108,but because the fluid level is above inlet 410, air cannot pass througheither. This causes a dramatic pressure drop (vacuum increase) throughline 126. Vacuum pressure transducer 124 is coupled to line 126measuring the negative pressure passing through canister 26, aspreviously discussed. If such a dramatic pressure drop occurs,transducer 124 will provide such data to controller 50 through line 128.Controller 50 will then know to shut the system down until the fullcanister is replaced with either an empty or only a partially fullcanister.

Another illustrative embodiment of a wound treatment apparatus is shownin FIG. 8 and is indicated by reference numeral 3. Apparatus 3 operatesin a similar manner as apparatus 2, with the exception of the use of two“intravenous-style” fluid bags 510, 512 suspended above housing 4 todispense the fluid. In this illustrated embodiment, posts 514, 516 withhooks 518, 520 extend upwardly of apparatus 3 from behind doors 32, 33.It will be appreciated that the posts 514, 516 may be extensible toelevate the bags 510, 512 to selected heights to provide selectedpressures for irrigation. A dispensing tube 18 extends from each bag510, 512 at one end and couples to each bandage. Gravity assists inmoving fluid through tubes 18 and into the bandages. A tube clip 522 iscoupled to each tube 18 and configured to pinch and close tube allowingthe caregiver to selectively prevent fluid from dispensing intobandages.

Illustrative vacuum bandage 314 of FIG. 3 is designed to provide aprotective environment around wound 300. Illustratively, such bandageslast for up to 7 days without having to be replaced. Bandage 314includes rinse and drain orifices (not shown) within the body of bandage314 that communicate with tubes 18, 20, respectively. Such orifices areillustratively 0.030-inch (0.08 cm) diameter and/or 0.040-inch (0.10 cm)diameter. Vacuum evacuating sub-system 66 cooperates with bandage 314,similar to bandage 14, to draw the fluid and exudate from the surface ofwound 300, and collect same into waste canister 26.

Examples of bandages 14 and 15 are shown in U.S. patent application Ser.No. 09/725,352, entitled VACUUM THERAPY AND CLEANSING DRESSING FORWOUNDS, filed on Nov. 29, 2000, and assigned to the same Assignee orAffiliated Assignee as the present disclosure, and the completedisclosure of which is hereby expressly incorporated by reference. It isfurther contemplated that other bandages may be used with this controlsystem, including bandages having separate irrigation and vacuum ports.Examples of such bandages are shown in U.S. patent application Ser. No.09/369,113, entitled WOUND TREATMENT APPARATUS, filed on Aug. 5, 1999,and assigned to the same Assignee or Affiliated Assignee as the presentdisclosure, and the complete disclosure of which is hereby expresslyincorporated by reference. The complete disclosure of U.S. patentapplication Ser. No. 10/144,504, entitled VACUUM THERAPY AND CLEANSINGDRESSING FOR WOUNDS and filed on May 13, 2002, is hereby expresslyincorporated by reference.

A side diagrammatic view of bandage 14 along with a portion of system 6is shown in FIG. 9. (See also FIG. 1.) Bandage 14 is of an illustrativetype for use with apparatus 2. (Note that the bandage is not drawn toscale.) As previously discussed, bandage 14 is a vacuum bandage. Bandage14 comprises a cover film 602, illustratively a flexible cover, thatseals wound 300 about its outer perimeter. It is contemplated, however,that film 602 can be made from an occlusive or semi-occlusive materialthat allows water vapor to permeate there through, but otherwiseprotects wound 300 from the outside environment. A bandage member 604 isplaced adjacent wound 300 and is configured to irrigate wound 300. Inthe illustrated embodiment, bandage member 604 comprises upper channels606 and lower channels 608, each provided on opposite sides 610, 612,respectively, of bandage member 604. Each of the upper channels 606 isgenerally congruent with one of the lower channels 608. Channels 606 and608 are in communication with each other via apertures 614. As shown inthe illustrated embodiment, side 612 of bandage member 604 faces wound300, and side 610 faces a porous packing 618. Packing 618 provided underfilm 602 to assist in providing a space 616 to facilitate the negativepressure. Packing 618 is typically a gauze material. It will beappreciated, however, that, for some wound care applications, thepacking 618 will not be used with member 604 under the film 602.

Illustratively, the caregiver may activate system 6, by means previouslydescribed, to draw exudate from wound 300 through channels 606, 608 andapertures 614 of bandage member 604, packing 618 and film 602, throughsplitter tube 620 connected to evacuating tube 20, and deposit incanister 26. The negative pressure applied to wound 300 created by pump110 can be applied for a period of time as determined by the caregiver.After a period of drawing, the caregiver may deactivate the negativepressure. The caregiver may begin irrigating wound 300 by releasingfluid from syringe 24, through tube 18, into splitter tube 620, throughfilm 602 and packing 618, and into bandage member 604. The fluid willtravel through channels 606 deposit in apertures 614 and irrigate wound300 by traveling through channels 608. Illustratively, the fluid willcontinue to irrigate wound 300 until space 616 can no longer receive anymore fluid. The fluid is held in space 616 for a period of time asdetermined by the caregiver. After that period, pump 110 is reactivatedand the fluid and exudate from wound 300 is evacuated from bandage 14and into canister 26 by the manner previously described. This process isrepeated as many times as necessary as determined by the caregiver.

In one embodiment, user interface 10 comprises a momentary switch (notshown) that selectively operates the aforementioned process. Forexample, the switch may be configured such that when the caregiverdepresses and holds the switch, the fluid will dispense from syringe 24into bandage 14. When the caregiver releases the switch the fluid willstop dispensing and pump 110 will activate and begin drawing the fluidand exudate. It is contemplated that the switch may be configured todelay between the vacuuming and dispensing for a period of time that isdefinable by the caregiver. It is also contemplated that all of theaforementioned descriptions as applied to system 6 are applicable tosystem 8.

The apparatus 2 is a portable, easy to use topical system that isintended to provide a protective/occlusive environment with features tofacilitate the administering of standard wound care. The apparatus 2provides for the care of two independently controlled wounds. Theapparatus 2 provides negative pressure to the wound bed, and thecaregiver can set the level of negative pressure. Illustratively, thenegative pressure is variable from 25-mmHg to 175-mmHg at increments of10 mmHg. The caregiver can choose between continuous, intermittent(profile), and no negative pressure modes. It will be appreciated thatthe apparatus 2 may be set up to provide various levels of vacuum atvarious times. The apparatus may be provided with the ability to pausenegative pressure therapy for set durations of time. The system may beset up to provide audible alarms to remind the caregiver to reset orstart a new cycle of vacuum therapy.

The apparatus 2 is intended to provide an occlusive wound healingenvironment. The apparatus 2 provides an active therapy unit thatdelivers drainage and cleansing for aggressive wound healing. It isintended, for example, for use on all pressure ulcers (Stage II throughStage IV), surgical draining wounds and leg ulcers.

In the illustrated embodiment, as shown in FIGS. 7 and 10, for example,canister 26 is configured to be received in cavity 9 disposed in side 38of housing 4. As shown specifically in FIG. 10, cavity 9 comprises twopull recesses 702, 704. Such recesses 702, 704 are concave-shapedportions formed adjacent to side 38 and to side walls 706 and 708.Recesses 702, 704 are provided to allow finger clearance when thecaregiver grasps grip portions 39, 40 of canister 26 to remove it from,or insert it into cavity 9. (See also FIGS. 1, 11 and 13.) Side walls706, 710 and bottom and top walls 708, 712 define cavity 9 such thatcavity 9 provides a relatively conforming receptacle for the canister26. The walls 706, 710 and 708, 712 conform to the size and shape of thepanels 714, 716, 718, 720 of canister 26. (See FIGS. 12 and 13.) Outlet412 of filter 108 mates with connector 416 to produce an air-tight sealbetween port 412 and connector 416. It is further contemplated thatother structures or configurations of outlet 412 and connector 416 canbe used to ensure system 6 is a closed system when canister 26 isproperly coupled to housing 4. It is still further contemplated that theaforementioned descriptions of canister 26 of system 6 apply equally tocanister 27 of system 8.

Each of top and bottom panel 718, 720 of canister 26 includes a boss722, 724, respectively. Each boss 722, 724 is configured to engage asensor such as sensor 116, 118, respectively, as depicted in FIG. 2.This engagement provides a signal to controller 50 indicating thatcanister 26 is seated properly into cavity 9 and the vacuum therapytreatment may begin to be administered. It is contemplated that bosses722, 724 can be mechanical sensors, optical, capacitive or other similartype sensors.

Side panels 714, 716 include buttons 726, 728 to assist the caregiver inplacing canister 26 in the proper location within cavity 9.Illustratively, buttons 726, 728 are small protrusions, each extendingfrom a side panel. Each button 726, 728 is configured to be received or“snapped” into corresponding dimples 730, 732, respectively, disposed inwalls 706, 710, respectively. In the illustrated embodiment, the buttonsextend from the widest point of side panels 714, 716 of canister 26.

Another wound treatment apparatus 802 is illustrated in FIG. 14.Apparatus 802 is similar in structure and function to apparatus 2,except as otherwise noted, so that identical reference numbers refer tosimilar components. Apparatus 802 has a pair of vacuum wound bandages14, a pair of dispensing lines 18, a pair of evacuating lines 20, and amain control unit 803 adapted for use with bandages 14 and lines 18, 20.Bandages 14, lines 18, 20, and control unit 803 cooperate to providedual vacuum therapy systems 806, 808.

Control unit 803 has a control module 810, a pair of fluid sources suchas syringes 24 coupled to dispensing lines 18 to provide fluid forirrigation of the wounds, and a pair of disposable waste collectioncanisters 826 coupled to evacuating lines 20 to collect waste materialsuch as exudate from the wounds and fluid from syringes 24, asillustrated in FIG. 14. Each dispensing line 18 and evacuating line 20is associated with one of bandages 14. Each syringe 24 and canister 826is provided for one of systems 806, 808. Control module 810 has ahousing 804. Syringes 24 are coupled to the front of housing 804 andcanisters 826 are coupled to the sides of housing 804, as discussed inmore detail below. Housing 804 has a handle 812 at the top thereof forhand-carrying control unit 803. A user interface 10 is centrally mountedto housing 804 between syringes 24 and canisters 826 to allow acaregiver to operate systems 806, 808.

Systems 806, 808 are similar to one another in structure and function.Thus, the following description of system 806 applies also to system808.

Housing 804 has a door 832 to partially cover syringe 24, as illustratedin FIG. 14. Door 832 is hinged to housing 804 by a pair ofvertically-spaced hinges 814 positioned along a laterally outer side 815of door 832 for movement of door 832 between opened and closedpositions. A rear side 816 of door 832 has a plurality ofvertically-spaced, horizontal mounts or grooves 817 (see FIGS. 14 and17) for receiving a flange 818 of syringe 24. Housing 804 also has aplurality of corresponding vertically-spaced, horizontal mounts orgrooves 820 (see FIGS. 14 and 17) for receiving flange 818. Duringinstallation of syringe 24, an end of a plunger 70 of syringe 24 isplaced on a vertically movable plunger interface 78 of a syringe drivemechanism, such as the one described above in connection with apparatus2, and flange 818 is inserted into one of grooves 820. Door 832 is thenclosed causing one of grooves 817 to receive flange 818 so that syringe24 is held in place by grooves 817, 820. Grooves 817, 820 supportsyringe 24 in a vertical orientation.

A door latch 822 is coupled to a laterally inner side 824 of door 832,as illustrated in FIGS. 14-16. Latch 822 is movable relative to door 832between a latched position (FIG. 16) blocking movement of door 832 fromits closed position to its opened position and a release position (FIGS.14-15) allowing door 832 to move between its closed position and itsopened position. Latch 822 has a fastener 828, such as an arm or lug,and an actuator 830 to pivot fastener 828 into and out of a slot 834 ofhousing 804 between the latched and release positions. Actuator 830 hasa stem 836 coupled to fastener 828 and a handle or door knob 838 coupledto stem 836 to rotate stem 836 and thus fastener 828 between the latchedand release positions when a caregiver rotates handle 838. Stem 836extends through an aperture of door 832. Handle 838 is coupled to oneend of stem 836 in front of door 832 and fastener 828 is coupled to anopposite end of stem 836 behind door 832.

Canister 826 is coupled to vacuum bandage 14 and other components ofapparatus 802, as illustrated, for example, in FIG. 27. Evacuating line20 is coupled to vacuum bandage 14 and an inlet port 850 of canister 826to introduce waste material into an interior region or chamber 866 ofcanister 826 through inlet port 850. A pressure sensor 124 is coupled toan upper pressure port 852 of canister 826 via a fluid line 854 (seeFIGS. 19 and 27) to sense the pressure in region 866. Pressure sensor124 sends a signal indicative of the sensed pressure to a controller850, which is common to both systems 806, 808, via an electrical line856 (see FIG. 27). A proportional valve 130 (see FIGS. 19 and 27) iscoupled to a lower outlet port 857 of canister 826 via a fluid line 858(see FIGS. 19 and 27). A pressure regulator 134 (see FIGS. 19 and 27) iscoupled to proportional valve 130 and a vacuum source 110 (see FIGS. 19and 27) via fluid lines 860 and 862, respectively (see FIG. 27). Vacuumsource 110 provides a negative or vacuum pressure within bandage 14through lines 862, 860, 858, 20 and regulator 134, valve 130, andcanister 826 to suction waste material into canister 826.

Vacuum source 110 continues to operate even if, for example, blockageoccurs somewhere upstream from vacuum source 110. If the blockagebecomes too great, vacuum source 110 could experience too great a load,or vacuum pressure. Pressure regulator 134 is provided to establish amaximum load that vacuum source 110 can experience. Pressure regulator134 allows air to be suctioned into line 862 when this maximum load isreached to protect vacuum source 110.

A filter 864 is positioned in interior region 866, as shown in FIGS. 20,23, and 27. Filter 864 covers pressure port 852 and outlet port 857 toprevent waste material from entering lines 856, 858 and possiblydamaging pressure sensor 124, proportional valve 130, pressure regulator134, or vacuum source 110. Filter 864 is, for example, a 1.0 micronteflon hydrophobic filter.

Controller 850, pressure sensor 124, and proportional valve 130cooperate to provide feedback control of the vacuum pressure provided tobandage 14. Controller 850 operates proportional valve 130 viaelectrical line 864 in response to the pressure sensed by pressuresensor 124 to provide a desired negative pressure in interior region866. A caregiver provides the desired negative pressure to controller850 through user interface 10. If, for example, pressure sensor 124senses a pressure in canister 826 that is more negative than the desirednegative pressure (which includes a suitable tolerance range),controller 850 will cause valve 130 to move closer toward its fullyclosed position so that interior region 866 experiences less of thesuction from vacuum source 110 and the pressure in canister 826 rises toapproach the desired negative pressure. On the other hand, if pressuresensor 124 sense a pressure in canister 826 that is more positive thanthe desired negative pressure, controller 850 will cause valve 130 tomove closer to its fully opened position so that interior region 866experiences more of the suction from vacuum source 110 and the pressurein canister 826 lowers to approach the desired negative pressure.

Based on readings from pressure sensor 124, controller 850 is able todetect when the waste material in canister 826 has reached a fill limit,which occurs when the waste material at least partially occludes outletport 857. As outlet port 857 becomes occluded due to the wetting offilter 864, the negative pressure established by vacuum source 110becomes blocked from interior region 866. The pressure sensed by sensor124 then begins to rise (i.e., become less negative) above the desirednegative pressure, especially if bandage 14 has a vent in communicationwith atmosphere, and air enters interior region 866 through bandage 14,line 20, and inlet port 850. In some embodiments, air enters interiorregion 866 through a bleed port (not shown) formed in housing 884 at anelevation higher than outlet port 857 instead of through the bandagevent or in addition to the bandage vent. In response to the pressurerise, controller 850 moves proportional valve 130 toward its fullyopened position to try to lower the sensed pressure to the desirednegative pressure. If vacuum source 110 is able to lower the sensedpressure to the desired negative pressure, the waste material fill limithas not been reached. If the sensed pressure remains above the desirednegative pressure, controller 850 opens proportional valve 130 furtherand compares the sensed pressure to the desired negative pressure.

Controller 850 determines that the waste material in canister 826 hasreached its fill limit when proportional valve 130 has been fully openedbut the sensed pressure remains above the desired negative pressure.This occurs because the waste material has occluded outlet port 857enough to prevent vacuum source 110 from being able to lower the sensedpressure to the desired negative pressure. Pressure sensor 124, however,is still able to sense the pressure within interior region 866 throughpressure port 852 because pressure port 852 is positioned at anelevation higher than outlet port 857. Controller 850 then activates analarm 868 via an electrical line 870 to alert a caregiver that canister826 is full and needs to be changed.

Housing 804 contains components of control unit 803, as illustrated inFIG. 19. Housing 804 has two receptacles 840, one receptacle 840 on eachside of housing 804, and each receptacle 840 is configured to receive arespective canister 826 therein. Housing 804 also has a removablevertical rear wall 842 (see FIG. 18). Behind rear wall 842 is a chamber871 (see FIG. 19). Each receptacle 840 extends toward a center ofchamber 871 from a side wall of housing 804. A printed circuit board(PCB) 872 is mounted to a rear surface of a front wall 873 of housing804 within chamber 871. Pressure sensors 124 and controller 850 aremounted to PCB 872 within chamber 871. Valves 130, pressure regulators134, vacuum sources 110, and lines 854, 858 are also positioned withinchamber 871.

A pair of mufflers 874 and a pair of muffler lines 876 are positionedwithin chamber 871. Each muffler line 876 is coupled to one of mufflers874 and one of vacuum sources 110. Illustratively, each muffler 874 hasthree disk filters 878 in series to provide three chambers 880 havingglass fiber material 882 therein to absorb sound energy. Adjacentfilters 878 are coupled together by luer-lock mechanisms.

A battery 954 rests on a bottom wall 956 of housing 804 in chamber 871,as illustrated in FIG. 19. A main power connection 958 is coupled tobattery 954 and to PCB 872. Battery 954 is illustratively a rechargeablenickel metal hydride battery that automatically recharges when mainpower connection 958 is coupled to an external electrical outlet (notshown) via a power cord (not shown), for example, and automaticallyprovides electrical power to the electrical components of control unit803 when battery 954 is charged and the power cord is disconnected fromthe external electrical outlet.

A mounting bracket 844 is coupled to an outwardly facing surface of rearwall 842, as illustrated in FIG. 18, to mount control unit 803 to asuitable control unit support (not shown). Bracket 844 has an envelope846 to receive the support through a lower opening 848. A horizontalupper wall 849 is coupled to the top of envelope 846. Envelope 846 hasinternal tapered walls 960 extending from the bottom of envelope 846 toupper wall 849. The control unit support wedges against tapered walls960 when it is inserted within envelope 846.

Canister 826 has a housing 884 providing interior region 866 to collectwaste material therein and a latch 886 to couple housing 884 to housing804 of control module 810, as illustrated in FIGS. 14 and 20-23.Canister 826 further has a cylindrical sleeve 888 carried by housing 884and extending horizontally through interior region 866. Ends of sleeve888 are appended to respective outer and inner vertical walls 891, 899of housing 884. Walls 891, 899 are each formed with an aperture 889 thatcommunicates with an interior region of sleeve 888. Latch 886 extendsthrough apertures 889 and sleeve 888 and engages a vertical back wall890 of receptacle 840, as described in more detail below.

Outer vertical wall 891 of housing 884 and sleeve 888 cooperate toprovide a monolithic unit that is coupled, such as by RF or ultrasonicwelding or adhesive, to a main portion 892 of housing 884 (see FIGS.20-23). An outer end portion 893 of sleeve 888 is formed monolithicallywith a recessed portion 894 of wall 891. Wall 891 has a peripheralflange 895 that is coupled to a corresponding peripheral flange 896 ofmain portion 892. An inner end portion 897 of sleeve 888 is coupled to arecessed portion 898 of inner vertical wall 899 of main portion 892.Outer wall 891 has inlet port 850 formed integrally therewith orappended thereto. Inner wall 899 has upper pressure port 852 and loweroutlet port 857 formed integrally therewith or appended thereto.

Latch 886 has a fastener 910 to couple to back wall 890 and an actuator912 to rotate fastener 910, as illustrated in FIGS. 21-23. Fastener 910has a pair of bayonet-style canted lugs 914 coupled to an inner endportion 916 of a shaft 918 of actuator 912. Lugs 914 are diametricallyopposed to one another and extend somewhat circumferentially and axiallyon shaft 918.

Actuator 912 further has a handle 920 coupled to an outer end portion922 of shaft 918, as illustrated in FIGS. 14, 20, 22 and 23. Handle hasa disk 924 coupled to end portion 922 and a flange 926 coupled to andextending radially outwardly from disk 924. Disk 924 and a portion offlange 926 are positioned within recessed portion 894. Recessed portion894 has a pair of stop edges 952 (see FIG. 20) positioned to restrictrotation of flange 926 to about 90 degrees.

A retainer 928 (see FIGS. 21-23) is mounted to shaft 918 between handle920 and fastener 910. Illustrative retainer 928 has a clip 930, such asan e-clip, and a clip mount 932. Clip mount 932 takes the form of a diskmounted to shaft 918 and has a circumferential groove 934 configured toreceive clip 930. Disk 932 has a diameter smaller than the innerdiameter of sleeve 888 to facilitate insertion of fastener 910 throughsleeve 888 during assembly of canister 826. After insertion of fastener910 through sleeve 888, clip 930 is positioned in groove 934 to engagerecessed portion 898 to prevent latch 886 from inadvertently withdrawingfrom sleeve 888. An inner portion of disk 932 is received in one ofapertures 889 and disk 924 is received in a space defined by an arcuateedge 950 (see FIGS. 20, 22, and 23) of wall 891 to support latch 886 forrotation relative to housing 884.

After latch 886 is coupled to housing 884, canister 826 is ready to beinstalled within receptacle 840. A caregiver places canister 826 withinreceptacle 840 (see FIG. 22) and inserts leading edges of lugs 914through an aperture 938 of back wall 890 shaped to receive lugs 914 (seeFIG. 24). The caregiver then rotates handle 920, and thus lugs 914, byhand, for example, approximately 90 degrees in a direction 936 (see FIG.25). This rotation causes lugs 914 to cam against inwardly facing thrustsurfaces 940 of back wall 890 (see FIG. 26) so that canister 826 movestoward back wall 890 and pressure port 852 and outlet port 857 are drawninto corresponding upper 904 and lower 906 sockets, respectively, ofback wall 890 (see FIGS. 22-23). Each port 852, 857 has a nipple 900that is inserted into the respective socket 904, 906 and an O-ring 902surrounding nipple 900. When lugs 914 are rotated against surfaces 940,nipples 900 are drawn into sockets 904, 906 so that O-rings 902sealingly engage tapered walls 908 of sockets 904, 906. Sockets 904, 906provide portions of lines 854, 858, respectively. A dome cover 942 ispositioned on an inner surface of back wall 890 and over lugs 914 andinner end portion 916 of shaft 918.

Canister 826 is removed from receptacle 840 and disposed of whencanister 826 is full of waste material. To do so, a caregiver removesline 20 from inlet port 850, places a cap (not shown) on port 850 toprevent spillage, and rotates handle 920 in a reverse direction 944 torelease lugs 914 from back wall 890. The caregiver then pulls on sidegrips 946 (see FIG. 14) of canister 826 to remove canister 826 fromreceptacle 840. As canister 826 is removed from receptacle 840, lugs 914pass back through aperture 938 and pressure port 852 and outlet port 857are withdrawn from upper and lower sockets 904, 906. Canister 826 canthen be discarded and a new, empty canister 826 can be installed withinreceptacle 840.

By having latch 886 included as part of canister 826, which is disposedof after being filled with waste material, latch 886 is not used overand over again, thereby preventing lugs 914 from wearing down anddegrading the sealed connection between ports 852, 857 and sockets 904,906.

User interface 10 is shown, for example, in FIG. 29. Interface 10 isdivided into a left side 1010 for operation of system 806 and a rightside 1012 for operation of system 808. Each side 1010, 1012 has anelectronic display 1013 to display various screens and a plurality ofuser input controls to control operation of the respective system 806,808. Each display 1013 includes, for example, a liquid crystal display(LCD) and backlighting provided by a column of LED's behind the LCD. Theuser controls include a home control or button 1014 to go to a homescreen 1015 (see FIG. 35) and a back control or button 1016 to navigateto a previous screen until the home screen is reached. The user controlsalso include up control or button 1018 and down control or button 1020for purposes described herein, an enter button 1022 to make variousselections, a flush or irrigation control or button 1024 to operate theirrigation mechanism discussed herein with respect to apparatus 2, 802and a pause control or button 1026 to suspend operation of therespective vacuum source 110.

One of the user controls is an alarm silence control or button 1028.Button 1028 is common to both systems 806, 808 to silence all audiblealarms of control unit 803 for a predetermined period of time, such asfifteen minutes. An LED illuminates button 1028 when button 1028 ispressed to indicate that all the audible alarms have been silenced.Pressing button 1028 again at any time during the predetermined timeperiod starts the predetermined time period over. It should beappreciated that the identified functions of buttons 1014, 1016, 1018,1020, 1022, 1024, 1026, 1028 are exemplary and that buttons 1014, 1016,1018, 1020, 1022, 1024, 1026, 1028 can be operated to provide otherfunctions as well.

Interface 10 also has a power LED 1030 and a battery LED 1032. Power LED1030 provides a visual indication when control unit 803 is powered on.Control unit 803 is powered on and off by a rocker switch (not shown).Battery LED 1032 provides a visual indication when control unit 803 isusing power from battery 954.

Control unit 803 is configured to operate in a power-saving mode after apredetermined period of time of inactivity. During this power-savingmode, the backlighting of displays 1013 is extinguished. Pressing any ofbuttons 1014, 1016, 1018, 1020, 1022, 1024, 1026, 1028 during thepower-saving mode deactivates the power-saving mode and turns thebacklighting back on. An alarm condition automatically deactivates thepower-saving mode.

Referring to FIG. 30, control unit 803 conducts a Power On Self Test(POST) when control unit 803 is powered on initially. During the POST,text 1031 appears on one of displays 1013 indicating the revision levelof the software of controller 850 and a countdown 1033 appears on theother display 1013 indicating the approximate time remaining to completethe POST.

During countdown 1033, a user, such as a service technician, cantransition control unit 803 to a calibration mode to calibrate pressuresensors 124. To make this transition, the user presses both pausebuttons 1026 simultaneously during countdown 1033 to cause a calibrationscreen 1036, as shown in FIG. 31, to appear on both displays 1013. Eachcalibration screen 1036 is associated with one of vacuum sources 110.

Once at calibration screen 1036, the user can calibrate one or bothpressure sensors 124. When control unit 803 is powered on, both vacuumsources 110 automatically begin to operate and both proportional valves130 are fully closed. Vacuum sources 110 continue to operate and valves130 remain in their fully closed position when the calibration modebegins. Since the procedure for calibrating pressure sensors 124 is thesame for both pressure sensors 124, the calibration procedure isdescribed for only one of them.

In general, two outputs of pressure sensor 124 are correlated to twocalibration pressures to calibrate pressure sensor 124. In oneembodiment, the first calibration pressure is, for example, 0millimeters of Mercury (or 0 mm Hg, i.e., atmospheric pressure) and thesecond calibration pressure is, for example, 225 mm Hg of negativepressure.

To obtain the first output of pressure sensor 124, a pressure sensor1038, such as a manometer, is positioned in communication with interiorregion 866 of canister 826, as shown diagrammatically in FIG. 32. Inparticular, sensor 1038 is coupled to inlet port 850 so that sensor 1038communicates with the pressure in interior region 866. Sensor 124 isalready positioned in communication with the pressure of interior region866 since sensor 124 is coupled to pressure port 852.

Valve 130 remains fully closed when control unit 803 enters thecalibration mode. Being fully closed, valve 130 blocks communicationbetween vacuum source 110 and interior region 866 so that atmosphericpressure is established in interior region 866. Sensors 124, 1038 thuscommunicate with atmospheric pressure at the beginning of thecalibration process.

When a user observes that sensor 1038 indicates the first calibrationpressure, the user operates a user control to store the output of sensor124 in controller 850 and thereby correlate that output to the firstcalibration pressure. For example, when the user observes that sensor1038 indicates a first calibration pressure of 0 mm Hg, the user presseshome button 1014 to store the corresponding analog-to-digital (A/D)output of sensor 124 in controller 850 as a first calibration settingand thereby correlate that output to 0 mm Hg (pressing home button 1014in this instance does not cause home screen 1015 to appear).Illustratively, the A/D output of sensor 124 can range from 0 to 4095.

The user then proceeds to correlate a second output from sensor 124 withthe second calibration pressure. Sensors 124, 1038 remain coupled toports 852, 850, respectively, and the user operates up and down buttons1018, 1020 as necessary to establish the second calibration pressure ininterior region 866 to cause sensors 124, 1038 to communicate with thesecond calibration pressure. In general, in the calibration mode,pressing up button 1018 raises the pressure in interior region 866(i.e., makes the pressure more positive) by moving valve 130 toward itsfully closed position so that vacuum source 110 establishes lessnegative pressure in interior region 866. On the other hand, pressingdown button 1020 lowers the pressure in interior region 866 (i.e., makesthe pressure more negative) by moving valve 130 toward its fully openedposition so that vacuum source 110 establishes more negative pressure ininterior region 866. To provide a second calibration pressure of 225 mmHg of negative pressure in interior region 866, valve 130 is openedsomewhat to permit communication between vacuum source 110 and interiorregion 866.

When the user observes that sensor 1038 indicates the second calibrationpressure, the user again operates a control to correlate the output ofsensor 124 with the second calibration pressure. For example, when theuser observes sensor 1038 indicate a second calibration pressure of 225mm Hg of negative pressure, the user again presses home button 1014 tostore the corresponding A/D output of sensor 124 in controller 850 as asecond calibration setting and thereby correlate that output of sensor124 with 225 mm Hg of negative pressure. The calibration process iscompleted once the second calibration setting is obtained. Controller850 then uses the first and second calibration settings to controlvacuum source 110 to provide a desired pressure from the entire range ofpossible pressures in canisters 826.

Calibration screen 1036 provides calibration information for the user.Calibration screen 1036 has text 1042 providing the current pressurereading in mm Hg of sensor 124, the percentage that valve 130 is open,the A/D output of sensor 124, the first calibration setting, and thesecond calibration setting.

Calibration screen 1036 also provides calibration information toinstruct a user when control unit 803 is in the calibration mode.Information 1044 at the top of calibration screen 1036 instructs theuser to set the pressure to 0 mm Hg at the beginning of the calibrationprocess. Information 1046 indicates that up and down buttons 1018, 1020can be operated to change the position of valve 130. Information 1048indicates that home button 1014 can be operated to store the calibrationsettings. Information 1049 provides that the calibration mode can beexited by pressing enter button 1022.

Control unit 803 has a time meter 1052 (see FIG. 27) associated witheach vacuum source 110 to keep track of how long the associated vacuumsource 110 has operated. Based on the operation of time meter 1052, avalue indicative of how long vacuum source 110 has operated is stored ina memory location of controller 850. The value indicative of how longvacuum source 110 has operated is updated by controller 850 and isdisplayed during calibration of controller 850. Each calibration screen1036 displays the total number of hours of use of the associated vacuumsource 110 in line of text 1050.

As indicated by text 1051 (see FIG. 31), an alarm log 1052 (see FIG. 33)associated with each alarm 868 is accessed by pressing the associatedpause button 1026 in calibration screen 1036. When pause button 1026 onleft side 1010 is pressed in the calibration screen 1036, display 1013on left side 1010 displays an alarm log screen 1054 having an alarm log1052 associated with alarm 868 of system 806. When pause button 1026 onright side 1010 is pressed in the calibration screen 1036, display 1013on right side 1010 displays alarm log screen 1054 having alarm log 1052associated with alarm 868 of system 808. Each alarm log 1052 lists allactivations of the associated alarm 868 occurring within the previous 48hours and provides information regarding the alarm activations includinghow long ago the activations occurred, descriptions of the activations,and error codes associated with the activations.

Alarm log screen 1054 provides navigation information for a user at thebottom of the screen. Exit information 1049 instructs that pressingenter button 1022 will cause the respective display 1013 to exit thealarm log screen 1054. Display 1013 returns to calibration screen 1036when alarm log screen 1054 is exited. Page down/page up information 1055instructs that pressing down button 1020 will cause the associateddisplay 1013 to display the next page of alarm log 1052 and pressing upbutton 1018 will cause the associated display 1013 to display theprevious alarm log 1052.

When calibration screen 1036 is exited, a patient settings screen 1056appears on one of displays 1013, as shown in FIG. 34. The user isprompted to select whether control unit 803 will be used for a “NewPatient” or the “Same Patient” (i.e., the most recent patient for whichthe system was used). Selecting “New Patient” restores the systemdefault settings and allows the user to select new patient settings.Selecting “Same Patient” causes the system to retain the most recentlystored patient settings. Patient settings screen 1056 providesinformation 1058 at the bottom of the screen instructing that up anddown buttons 1018, 1020 can be used to toggle between the “New Patient”and “Same Patient” options and instructing the user to press enterbutton 1022 when the user has made a selection. Pressing enter button1022 when the “New Patient” option is selected causes home screen 1015,shown, for example, in FIG. 35, to appear on display 1013 to allow theuser to select new patient settings. If the “Same Patient” option isselected when enter button 1022 is pressed, the most recently storedpatient settings will be accepted and control unit 803 will be ready forwound therapy.

In home screen 1015, information 1060 at the top of the screen instructsthe user to select one of four modes for system 806 and system 808, asshown in FIG. 35. The four modes are labeled as “Continuous,” “Profile,”“Off,” and “History,” each of which is explained in more detail below.By default, the Continuous mode is selected for system 806 on left side1010 and the Off mode is selected for system 808 on right side 1012. Bypressing up and down buttons 1018, 1020, the user can toggle between thefour modes to select any one of them. Information 1062 at the bottom ofhome screen 1015 instructs the user to press enter button 1022 when theuser has selected one of the four modes for the respective system 806,808 to confirm the selection.

In Continuous mode, the user can select a desired negative pressuresetting to be applied to the respective wound 16 by the respectivesystem 806, 808. Selection of Continuous mode in home screen 1015 causesa first continuous mode screen 1064 to appear on the respective display1013, as shown with respect to display 1013 on left side 1010 in FIG.36. The default desired negative pressure setting of 125 mm Hg for therespective vacuum source 110 appears in flashing text 1066 in screen1064. The user can change the desired negative pressure setting bypressing up and down buttons 1018, 1020, as indicated by information1067 displayed on screen 1064. The desired negative pressure setting canbe increased or decreased within a range of 25 mm Hg to 175 mm Hg in 10mm Hg increments. Pressing enter button 1022 will accept the new desirednegative pressure setting and initiate operation of the respectivevacuum source 110 for wound therapy.

Once wound therapy begins, the respective system 806, 808 remains incontinuous mode and a second continuous mode screen 1070 (see FIG. 37)appears on the respective display 1013. Screen 1070 provides the currentdesired negative pressure setting 1071, information 1072 indicating thatthe user can go back to first continuous mode screen 1064 by pressingbutton 1016 to change the desired negative pressure setting, andinformation 1074 indicating that the user can go to home screen 1015 bypressing home button 1014.

In Profile mode, the user can select the maximum and minimum negativepressure settings that the respective system 806, 808 can apply to therespective wound 16. Selection of the Profile mode in home screen 1015causes a first profile mode screen 1076 to appear on the respectivedisplay 1013, as shown with respect to display 1013 on right side 1012in FIG. 36. The default maximum and minimum negative pressure settingsof 125 mm Hg and 25 mm Hg, respectively, appear on screen 1076 with themaximum negative pressure setting appearing in flashing text 1078. Theuser can change the maximum negative pressure setting by increments of10 mm Hg by pressing up and down buttons 1018, 1020, as indicated byinformation 1080 displayed on screen 1076. Pressing enter button 1022will accept the maximum negative pressure setting on screen 1076, asindicated by information 1082, and cause a second profile mode screen1083 to appear on display 1013.

In second profile mode screen 1083, the minimum negative pressuresetting appears in flashing text 1084 (see FIG. 37). As with the maximumnegative pressure setting, the user can change the minimum negativepressure setting by increments of 10 mm Hg by pressing up and downbuttons 1018, 1020, as indicated by information 1086 on screen 1083.Pressing enter button 1022 will accept the minimum negative pressuresetting on screen 1084, as indicated by information 1082. Once themaximum and minimum negative pressure settings are selected, therespective system 806, 808 is ready for wound therapy and a thirdprofile mode screen 1088 (see FIG. 38) appears on the respective display1013. In screen 1088, the maximum and minimum negative pressure settingsare displayed and information 1090 is provided to inform the user thatpressing back button 1016 will allow the desired negative pressuresetting to be changed and pressing home button 1014 will cause homescreen 1015 to appear.

Pressing pause button 1026 suspends operation of the respective vacuumsource 110 during Continuous or Profile mode for a predetermined timeperiod, such as 15 minutes. A pause screen 1096 appears on therespective display 1013 when a user presses the pause button 1026associated with that display 1013, as shown with respect to display 1013on left side 1010 in FIG. 38. Text 1098 appears in pause screen 1096 toprovide the number of minutes remaining during the pause period.Information 1099 is provided at the bottom of pause screen 1096providing that pressing pause button 1026 again will end the pauseperiod and resume the previous activity.

Selection of Off mode at home screen 1015 causes operation of therespective system 806, 808 to be suspended. An off mode screen 1088 (seeFIG. 40) appears on the respective display 1013 during Off mode andinformation 1089 at the bottom of screen 1088 indicates that pressinghome button 1014 will cause home screen 1015 to reappear.

Selection of History mode at home screen 1015 causes a history screen1092 to appear on the respective display 1013, as shown in FIGS. 39 and40. Screen 1092 provides history information relating to activity of therespective system 806, 808 for the previous 48 hours in which controlunit 803 was powered on. In particular, the history information includesin table format the negative pressure settings associated with therespective mode (i.e., Continuous, Profile, Off) occurring at the end ofeach of the 48 hours, whether the respective irrigation mechanism wasactivated during the respective hour (as indicated by a liquid dropsymbol 1093), and the number of minutes that the respective system 806,808 provided wound therapy during the respective hour. Exit information1049 is provided at the bottom of screen 1092 to instruct a user thatHistory mode can be exited by pressing enter button 1022. One or both ofinformation 1094 and information 1095 are also provided at the bottom ofscreen 1092 to instruct a user that up and down buttons 1018, 1020 canbe operated to move between pages in History mode.

Pressing irrigation button 1024 while the respective system 806, 808 isin the Continuous, Profile, or Off mode causes a flush start screen 1100(see FIG. 41) to appear on the respective display 1013. Screen 1100provides irrigation information 1102 instructing a user how to use therespective irrigation mechanism. Information 1102 instructs the user toset a switch or stopcock 1101 (see FIGS. 1 and 14) associated with theirrigation mechanism to a flush position to place the respective vacuumwound bandage 14, and thus the respective wound 16, in communicationwith the respective syringe 24. Information 1102 next instructs the userto press and hold irrigation button 1024 to operate the irrigationmechanism for irrigation of the respective wound 16. Information 1103provides that pressing the respective enter button 1022 will end theirrigation procedure to reinitiate vacuum therapy.

Irrigation button 1024 is a momentary switch so that irrigation occursonly when irrigation button 1024 is pressed. When irrigation button 1024is pressed for irrigation, a flush active screen 1104 (see FIG. 41)appears on one of displays 1013 with flashing text 1105 to indicate thatthe respective wound 16 is being irrigated or flushed.

When irrigation button 1024 is released, a flush finish screen 1106appears, as shown in FIG. 42. Screen 1106 provides information 1108 atthe top thereof to indicate that the user can press irrigation button1024 again to provide more irrigation. Screen 1106 also providesinformation 1110 instructing the user what to do if irrigation iscompleted. Information 1110 instructs the user to switch stopcock 1101back to the vacuum position to place the respective vacuum wound bandage14, and thus the respective wound 16, in communication with therespective vacuum source 110 and then to press enter button 1022 to endthe irrigation procedure to reinitiate vacuum therapy. Flush screens1100, 1104, 1106 cooperate to provide a flush or irrigation menu.

Controller 850 is configured to cause displays 1013 to display messagesrelating to three types of alarm conditions. Those alarm conditions canbe referred to as a Reminder condition, an Alarm condition, and aService Required condition, each of which is discussed in turn. Suchalarm conditions are deviations from normal operation of the respectivesystem 806, 808.

Alarm activations from Reminder conditions are shown in FIGS. 43, 44,and 48. Conditions that result in such alarm activations includepressing irrigation button 1024 when the respective syringe 24 is empty(see screen 1109 in FIG. 43), pressing irrigation button 1024 when therespective door 832 is open (see screen 1111 in FIG. 43), activating theContinuous or Profile mode when the respective waste collection canister826 is not positioned within its receptacle 840 (see screen 1112 in FIG.44), and when the flush menu is exited (see screen 1114 in FIG. 48).

In each of screens 1109, 1111, 1112, 1114, the text “Reminder” appearsand information 1116, 1118 is displayed informing the user of thecondition and how to troubleshoot the condition. In screen 1109,information 1116 informs the user that the respective syringe 24 isempty and information 1118 instructs the user to install another syringe24. In screen 1111, information 1116 informs the user that therespective door 832 is open and information 1118 instructs the user toshut the door 832. In screen 1112, information 1116 informs the userthat the respective canister 826 is missing and information 1118instructs the user to install the canister 826. In screen 1114,information 1116 informs the user that the position of stopcock 1101 isincorrect and information 1118 instructs the user to set stopcock 1101to its vacuum position.

When an alarm activation due to a Reminder condition occurs, therespective screen 1109, 1111, 1112, 1114 appears on the respectivedisplay 1013 for a predetermined period of time, such as five seconds,and audible alarm 868 is activated for another predetermined period oftime, such as one second. The screen then disappears and the respectivesystem 806, 808 continues in its previous mode.

A screen with the word “Alarm” appears on the respective display 1013and audible alarm 868 activates when an Alarm condition occurs, as shownin FIGS. 42 and 44-48. Information 1120, 1122 is provided on therespective screen to indicate the condition and how to troubleshoot thecondition.

Examples of Alarm conditions are shown in FIGS. 42 and 44-48. A screen1124 (see FIG. 42) provides information 1120 to alert the user that oneof the flush screens 1100, 1106 has been inactive for a predeterminedperiod of time, such as one minute, and information 1122 to instruct theuser how to remedy that condition. A screen 1123 (see FIG. 44) providesinformation 1120 to alert the user that one of waste collectioncanisters 826 is removed from its respective receptacle 840 duringoperation of the respective vacuum source 110 and information 1122 toinstruct the user to install the removed canister 826 and press enterbutton 1022 when installation is complete.

A screen 1126 (see FIG. 45) provides information 1120 to alert the userof an occluded system and information 1122 to instruct the user to checkfor a kinked or blocked hose and to check whether stopcock 1101 is inits flush position and then press enter button 1022 when finishedunkinking or unblocking the hose or moving stopcock 1101 to its vacuumposition.

A screen 1128 (see FIG. 45) provides information 1120 to alert the userthat vacuum wound therapy has stopped and information 1122 to instructthe user to check for a full waste collection canister 826, loose filmdressing, or improper hose connection and then press enter button 1022when finished correcting the condition that caused the alarm.

A screen 1130 (see FIG. 46) provides information 1120 to alert the userthat control unit 803 is tilted beyond forty-five degrees therebycausing wound therapy to be suspended and information 1122 to instructthe user to level control unit 803. A screen 1132 (see FIG. 47) providesinformation 1120 to alert the user that battery 954 is nearing the endof its electrical charge (e.g., battery 954 has about fifteen minutes ofelectrical charge remaining) and information 1122 to instruct the userto check the power cord of control unit 803. A screen 1134 (see FIG. 47)provides information 1120 to alert the user that battery 954 will soon(e.g., in about two minutes) reach the end of its electrical charge andinformation 1122 to instruct the user to again check the power cord ofcontrol unit 803 and to advise the user that therapy is suspended. Whenscreen 1134 appears, the respective alarm 868 will sound continuouslyuntil the power cord is plugged into an electrical power outlet andcontrol unit 803 will stop providing vacuum therapy.

A screen 1136 (see FIG. 48) provides information 1120 to alert the userif plunger interface 78 does not reach full travel within apredetermined period of time (e.g., within fifteen seconds) andinformation 1122 to instruct the user to check whether hose 18 isblocked or kinked and then to press enter button 1022 when finishedunkinking or unblocking the hose. Plunger interface 78 may also fail toreach full travel within the predetermined period of time becausestopcock 1101 is in its vacuum position instead of its flush position.

The user presses enter button 1022 after taking corrective measures toaddress the Alarm condition. If the Alarm condition has been corrected,no alarm 868 will sound, the respective screen 1123, 1124, 1126, 1128,1130, 1132, 1134, 1136 will disappear from the respective display 1013,and vacuum therapy will resume.

On the other hand, if the Alarm condition has not been corrected,pressing enter button 1022 will silence and reset the respective alarm868. However, the respective system 806, 808 will redetect the Alarmcondition and upon detection thereof the respective alarm 868 willactivate again and the respective screen 1123, 1124, 1126, 1128, 1130,1132, 1134, 1136 will reappear.

A Service Required screen 1138 (see FIG. 46) with the words “ServiceRequired” appears on the respective display 1013 when the respectivesystem 806, 808 needs to be serviced. Screen 1138 provides information1120 which provides an error code and information 1122 to instruct auser to call a service technician to address the problem associated withthe error code. Audible alarm 868 is activated when screen 1138 appears.It is intended that, in the event of a Service Required condition, aservice technician would provide the necessary service for therespective system 806, 808 and clear the alarm 868 caused by the ServiceRequired condition.

Although the foregoing apparatus has been described, one skilled in theart can easily ascertain the essential characteristics of the apparatus,and various changes and modifications may be made to adapt the varioususes and characteristics without departing from the spirit and scope ofthis disclosure, as described by the claims which follow.

What is claimed is:
 1. A method for calibrating a control unit adaptedto provide a negative pressure through a vacuum wound bandage associatedwith a wound of a patient, the method comprising positioning a firstpressure sensor in communication with the control unit, correlating afirst output of a second pressure sensor of the control unit to a firstcalibration pressure when the first pressure sensor senses the firstcalibration pressure, and correlating a second output of the secondpressure sensor to a second calibration pressure when the secondpressure sensor senses the second calibration pressure.
 2. The method ofclaim 1, wherein positioning a first pressure sensor in communicationwith the control unit includes positioning the first pressure sensor incommunication with a waste collection canister that is configured tocollect waste material from the vacuum wound bandage and communicateswith the second pressure sensor.
 3. The method of claim 2, whereinpositioning the first pressure sensor in communication with a wastecollection canister that is configured to collect waste material fromthe vacuum wound bandage and communicates with the second pressuresensor includes positioning the first pressure sensor in communicationwith a port configured to receive waste material from the vacuum woundbandage.
 4. The method of claim 2, wherein correlating a first output ofa second pressure sensor of the control unit to a first calibrationpressure when the first pressure sensor senses the first calibrationpressure includes establishing atmospheric pressure, which is the firstcalibration pressure, in the waste collection canister to cause thefirst pressure sensor and the second pressure sensor to communicate withatmospheric pressure.
 5. The method of claim 4, wherein establishingatmospheric pressure in the waste collection canister to cause the firstpressure sensor and the second pressure sensor to communicate withatmospheric pressure includes blocking communication between the wastecollection canister and a vacuum source.
 6. The method of claim 5,wherein blocking communication between the waste collection canister anda vacuum source includes closing a valve between the waste collectioncanister and the vacuum source.
 7. The method of claim 4, whereincorrelating a first output of a second pressure sensor of the controlunit to a first calibration pressure when the first pressure sensorsenses the first calibration pressure includes observing that the firstpressure sensor indicates that atmospheric pressure has been establishedin the waste collection canister.
 8. The method of claim 4, whereincorrelating a first output of a second pressure sensor of the controlunit to a first calibration pressure when the first pressure sensorsenses the first calibration pressure includes storing the first outputwhen the first pressure sensor indicates that atmospheric pressure hasbeen established in the waste collection canister.
 9. The method ofclaim 8, wherein storing the first output when the first pressure sensorindicates that atmospheric pressure has been established in the wastecollection canister includes operating a user control.
 10. The method ofclaim 2, wherein correlating a second output of the second pressuresensor to a second calibration pressure when the second pressure sensorsenses the second calibration pressure includes establishing the secondcalibration pressure, which is less than atmospheric pressure, in thewaste collection canister to cause the first pressure sensor and thesecond pressure sensor to communicate with the second calibrationpressure.
 11. The method of claim 10, wherein establishing the secondcalibration pressure, which is less than atmospheric pressure, in thewaste collection canister to cause the first pressure sensor and thesecond pressure sensor to communicate with the second calibrationpressure includes moving a valve to permit communication between thewaste collection canister and a vacuum source.
 12. The method of claim10, wherein establishing the second calibration pressure in the wastecollection canister to cause the first pressure sensor and the secondpressure sensor to communicate with the second calibration pressureincludes operating a user control.
 13. The method of claim 1, whereincorrelating a second output of the second pressure sensor to a secondcalibration pressure when the second pressure sensor senses the secondcalibration pressure includes operating a vacuum source of the controlunit to provide the second calibration pressure.
 14. The method of claim1, wherein correlating a first output of a second pressure sensor of thecontrol unit to a first calibration pressure when the first pressuresensor senses the first calibration pressure includes storing the firstoutput when the first pressure sensor senses the first calibrationpressure.
 15. The method of claim 14, wherein correlating a secondoutput of the second pressure sensor to a second calibration pressurewhen the second pressure sensor senses the second calibration pressureincludes storing the second output when the first pressure sensor sensesthe second calibration pressure.
 16. The method of claim 1, furthercomprising displaying calibration information on a display of thecontrol unit.
 17. The method of claim 1, wherein positioning a firstpressure sensor in communication with the control unit includespositioning a manometer in communication with the control unit.